hierarchy of nursing profession in ireland

I am a 25 year old nurse who is living in Portugal.
By the summer of 2012 I expect to be living in Dublin with my partner...
the application process and the registration with an bord altranais are in full swing...
but I am having a very hard time understanding what all of these different names mean...staff... clinical... general nurse even sister nurse??
Please if the is someone out there that could help me or tell me where I could find some information on this subject of hierarchy in ireland please do!Thank you.